Introduction to Human Anatomy and Physiology

Introduction to Human Anatomy and Physiology

After studying this chapter, readers should be able to

1. Define anatomy and physiology.

2. Name the components that make up the organization levels of the body.

3. Describe the major essentials of life.

4. Define homeostasis and describe its importance to survival.

5. Describe the major body cavities.

6. List the systems of the body and give the organs in each system.

7. Describe directions and planes of the body.

8. Discuss the membranes near the heart, lungs, and abdominal cavity.

9. List the nine abdominal regions.

10. Compare positive and negative feedback mechanisms.

Overview

The study of anatomy and physiology is vital for all health professionals and it involves many different areas of science to understand how the human body works and how it is structured. The study of anat-omy and physiology provides answers to many questions about the functions of the body in both health and disease. As a result of this understanding, it is possible to see what happens to the body when it is injured, stressed, or contracts a disease or infection. It is important for all allied health students to be familiar with the terminology used in anatomy and physiology. In this chapter, the focus is on a complete introduction to anatomy and physiology.

The structures and functions of the human body are closely related. Anatomy is the study of the struc-ture of body parts and how they are organized. This term is derived from the Greek words meaning tocut apart.Physiologyis the study of how body partswork. Every body part functions to assist the human body in different ways. It is not easy to separate the topics of anatomy and physiology because the struc-tures of body parts are so closely associated with their functions. Each part has its own unique substruc-tures that allow it to perform its needed functions.

Pathophysiology­ is the study of changes associatedwith, or resulting from, disease or injury. It is also con-cerned with biological and physical manifestations of disease as they relate to underlying abnormalities and physiological disturbances. Pathophysiology explains the processes within the body that result in disease signs and symptoms but does not focus directly on the treatment of disease.The human body has been studied for hundreds of years. Even though its inner workings are well under-stood, new discoveries are being made even today.

In 2003, the human genome (instructions that allow the body to operate) was deciphered for the first time. There are more than 20,000 genes in the human body, and this substantial discovery took many years to complete. Researchers frequently discover new infor-mation about physiology, particularly at the molecular level, but basic human anatomy changes very slowly.

Classifications of Anatomy

The many subdivisions of anatomy include gross (macroscopic) anatomy, microscopic anatomy, and developmental anatomy. These can be further broken down as follows:

■■ Gross (macroscopic) anatomy: The study oflarge body structures that can be seen without a microscope. These include the brain, heart, kidneys, lungs, and skin. Studies conducted to understand gross anatomy made use of dissected animals and their organs.

Regional anatomy: All structures in a cer-tain body region are examined at the same time. For example, for an arm, the structures being examined would include skin, muscles, bones, nerves, blood vessels, and others.

Systemic anatomy: Each body system isexamined. For example, the heart would be examined when studying the cardiovascular system, but so would all the blood vessels in the body.

Surface anatomy: This is the examinationof internal structures related to overlying skin surfaces. Surface anatomy is used, for example, to locate the correct blood vessels used for phlebotomy.

■■ Microscopic anatomy: The study of small bodystructures that require a microscope to be seen.

This requires making thin slices of tissues, which are then stained and affixed (mounted) to glass slides for microscopic examination.

Cytology: A subdivision of microscopicanatomy that focuses on body cells.

Histology: A subdivision of microscopicanatomy that focuses on body tissues.

■■ Developmental anatomy:The study of structural changes in anatomy throughout the life span.

Embryology: A subdivision of developmen-tal anatomy that focuses on developmental changes occurring before birth.

For medical diagnosis, scientific research, and other highly specialized needs, pathological or radio-graphic anatomy may be used. Pathological anatomyfocuses on disease and the structural changes that are a result of the disease, whereas radiographic anatomy focuses on internal structures via the use of X-rays or specialized scanning equipment such as magnetic resonance imaging (MRI) or computed tomography (CT). Molecular anatomy focuses on the structure of chemical substances (biological molecules). Although formally considered a branch of biology, molecular anatomy is still part of the overall study of anatomy as it focuses on subcellular particles of the body.

Anatomical studies require a combination of many different skills. These include anatomic terminology, observation, auscultation (using a stethoscope to listen to organ sounds), manipulation, and palpation (feeling body organs for normal or abnormal conditions by using the hands).

Classifications of Physiology

Physiology is concerned with how the body func-tions, often focusing on cellular or molecular activi-ties. There are also many subdivisions of physiology, which are primarily focused on certain organ sys-tems. Examples of physiology classifications are as follows:

■■ Respiratory physiology: Focuses on the functions of the respiratory system

■■ Cardiovascular physiology: Focuses on the heart and blood vessels

■■ Neurophysiology: Focuses on the nervous system

■■ Renal physiology: Focuses on the functions of the kidneys, including urine production

The physiology of the human body is based on chemical reactions that affect the actions of cells at the molecular level. Physiology is also linked to the study of physics, which takes into account body functions such as blood pressure, electrical currents, and mus-cular movement.

1. Describe the difference between gross anatomy and developmental anatomy.

2. Compare cytology and histology.

3. Explain the classifications of physiology.